Listing Guideline

When phytoplankton or zooplankton community structure significantly diverges from unimpacted control sites of comparable physical and chemical characteristics. In addition, this use will be considered impaired when relevant, field- validated, phytoplankton or zooplankton bioassays (e.g. Ceriodaphnia; algal fractionation bioassays) with appropriate quality assurance/quality controls confirm toxicity in ambient waters.

Delisting Guideline

When phytoplankton and zooplankton community structure does not significantly diverge from unimpacted control sites of comparable physical and chemical characteristics. Further, in the absence of community structure data, this use will be considered restored when phytoplankton and zooplankton bioassays confirm no significant toxicity in ambient waters.

Delisting Targets

A stepped approach is needed for delisting for this impairment:

  • The first step toward delisting will be to establish a baseline condition for the estuary to evaluate the extent of this impairment.  Phytoplankton and zooplankton community surveys should be conducted and compared to a non-impacted or minimally impacted reference site to set the baseline condition.  If the community structure is statistically different than the reference conditions, this BUI should be considered impaired.
  • Identify the factors leading to this impairment. 
    • Ambient water chemistry sampling should be conducted to determine if nutrient enrichment is the main contributor.  If nutrients are the main contributor, sources causing nutrient enrichment to the outer harbor and nearshore waters are identified and controlled.
    • If nutrient enrichment is not considered the cause of the impairment, conduct bioassays to determine if ambient water toxicity is causing impairment.

Sources of Pollution or Problem

  • Contaminated sediments; spills of chemicals within the watershed; atmospheric deposition
  • Sediment, nutrients, and bacteria as a result of nonpoint, or diffuse, sources of pollution; urban stormwater runoff; sewer overflows; noncontact cooling water
  • Dams, drop structures, concrete-lined channels, and poorly-sized culverts and stream crossings; shoreline alteration, such as sheet piling, that doesn’t provide high-quality habitat

Remediation Actions

Results from the plankton assessments in 2012 & 2014 are pending. The data from 2012 is being reassessed using the same statistical analysis as the 2014 data. The final report will include both data sets and final conclusions and is expected in late 2015 or early 2016.

Moving Forward

The next step will be to evaluate the findings of the USGS study from 2012 and 2014. If the planktonic community is found to be impaired compared to other Lake Michigan rivers, then investigate if nutrient enrichment and/or toxicity are causes of the plankton impairment. This determination would inform any additional necessary management actions. A target adjustment may also be needed depending on the results of the study.

Sources of contamination to the AOC need to be remediated. The following actions need to be completed in order to determine contamination related management actions.

  • Assess areas on the Milwaukee River from Estabrook Park dam downstream to the estuary.
  • Assess the potential impacts to sediments from other manufactured gas plants within the AOC.
  • Review and act upon sediment assessment data from other areas of the AOC. This includes, but is not limited to, Kinnickinnic River/Turning Basin, Menomonee River from confluence with Little Menomonee to the harbor and existing Milwaukee River data. The following management actions are necessary to move towards removing this impairment. This list is not complete. The actions that have been implemented are italicized.

1) Sources of contamination to the benthic community within the AOC need to be remediated.

  • Complete the assessment and cleanup of PCBs at the Cedar Creek Superfund Alternative Site.
  • Complete the management of sediments containing PAHs and metals from the Burnham Canal Superfund Alternative Site.
  • Complete the assessment of contaminated sediment and evaluate and implement clean up related to the Solvay Coke Superfund Alternatives Site.
  • Blatz Pavilion, Lincoln Park Phase 1 and Phase 2 Contaminated Sediment Remediation
  • Kinnickinnic River Legacy Act Cleanup


A full assessment of the impairment cannot be made until the final data from 2012 and 2014 are received from USGS.

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